rafflesia (răflēˈzhə) [key], any of a genus ( Rafflesia ) of parasitic plants native to the rain forests of the Malay peninsula, Sumatra, Borneo, and the Philippines. The plants have no roots, stems, or leaves, consisting of threadlike growths on the tissues of the vine that hosts them. They produce large buds that may take 10 months to open into huge five-petaled flowers, which in the largest species ( Rafflesia arnoldii ) measure a yard (1 m) or so across. The flowers of most species have the distinctive odor of rotting flesh. All species are endangered or threatened. Rafflesia species are classified in the division Magnoliophyta, class Magnoliopsida, order Rafflesiales, family Rafflesiaceae.